Prior art manufacturing methods for an organic light-emitting diode (OLED), for example an OLED intended for lighting purposes, usually involve a number of photolithography steps for applying the various metal layers required for the electrical connections of the device. Photolithography is very complex and expensive, so that alternative approaches are being sought. For example, a cost-efficient way of applying structured metal contact pads (anode and cathode) for current distribution on a substrate is to print a strip of metal ink onto the substrate to obtain a conductive strip with the desired dimensions. These printed strips are then annealed to improve their conductivity. Silver inks are very suitable for such printing techniques on account of their favourable thermal properties and relatively high conductivity. Anode and cathode contact pads printed using an ink can have a thickness of only 300 nm to 10 μm. However, even though the electrical properties of silver are very favourable, such thin silver layers can suffer from corrosion when exposed to humidity and oxygen, especially under the presence of an electrical bias, which is the case when a voltage is applied across the anode and cathode contact pads of an OLED device. This corrosion can ultimately interrupt the electrical connection between the power supply and the OLED device, resulting in device malfunction. Therefore, prior art manufacturing methods usually use a corrosion-resistant metal for the contact pads. Corrosion-resistant metals—for example chromium, molybdenum, gold, etc.—have the disadvantage that they are unsuited to a printing process, and must therefore be applied using the more expensive and time-consuming vacuum sputter process.
It is therefore an object of the invention to provide a more economical way of manufacturing an OLED device with a favourably long lifetime.